1) Field of the Invention
The present invention relates to a modified cyclic aliphatic polyamine. The present invention also relates to a curing agent for epoxy resin containing the modified cyclic aliphatic polyamine, an epoxy resin composition containing the curing agent for epoxy resin, and an epoxy resin cured product obtained by curing the epoxy resin composition. In the present invention, the term “cyclic aliphatic” includes a cycloaliphatic compound and an aliphatic heterocyclic compound.
The modified cyclic aliphatic polyamine is applicable to a curing agent for epoxy resin and a raw material for curing agent thereof to be utilized in an extremely wide field including application to a coating material such as an electrodeposition coating for motor car, a heavy-duty anticorrosion paint for ship, bridge, and land and marine iron structure, and inner coat for drinking can; application to electricity and electronics to be used in household electric products, communication equipments and control systems of motor car and airplane such as a laminated plate, an electric semiconductor sealing compound, an insulating powder coating, and coil impregnation; application to a civil engineering and construction material such as earthquake-proof of bridge, lining, reinforcement and repair of concrete structure, a flooring material of building, lining of water supplying facility and sewerage, and pavement for waste water and permeating water; application to an adhesive for vehicle and airplane, and application to composite materials for airplane, industrial materials and sports equipment and to a chain extender and a raw material for chain extender thereof of a polyurethane resin to be utilized in a very wide field including clothes, sports equipments, home appliances, electronics, medical apparatuses, motor cars, transporting apparatus, civil engineering and construction and industrial materials as foam, elastomer, coating, adhesive, binder, fiber, leather, flooring material, water proof material, athletic material, sealant, coking, medical material and fiber treating agent.
2) Related Art
It has widely known that various polyamines are used as a curing agent for epoxy resin and a raw material for curing agent thereof or a chain extender for polyurethane resin and a raw material for chain extender thereof.
Representative examples of the polyamines are as follows: aliphatic polyamines such as ethylenediamine, diethylenetriamine, triethylenetetramine, tetraethylenepentamine, pentaethylene hexamine, hexamethylenediamine, polyoxypropylenediamine and polyoxypropylenetriamine; alicyclic polyamines such as menthanediamine, isophoronediamine, bis(aminomethyl) cyclohexane, diaminodicyclohexylmethane, bis(4-amino-3-methylcyclohexyl) methane, N-aminomethylpiperazine, and norbornanediamine; aliphatic polyamines having aromatic ring such as xylylenediamine; aromatic polyamines such as phenylenediamine, diaminodiphenylmethane, diaminodiphenylsulfone, and diethyltoluenediamine.
However, these polyamines are scarcely used as it is as a curing agent for epoxy resin without any modifications. In most cases, they are used after various modifications suitable for their own characteristics caused by the reactivity of their amino groups, namely their active hydrogen atoms that each polyamine has, depending on the intended purpose such as an improvement of safety and hygiene, an improvement of workability and imparting of adequate property of cured products suitable for their own application.
Representative methods for a modification of polyamines include 1) a modification by Mannich reaction with a phenol compound and an aldehyde compound, 2) a modification by reaction with an epoxy compound, 3) a modification by reaction with a compound having a carboxyl group, 4) a modification by Michael reaction with an acryl compound and 5) combinations of any of 1) to 4).
By these modifications, a reduction of harmful vapor, an improvement of the property of exothermic reaction at the time of curing and an improvement of an adhesion property, water resistance and chemical resistance of cured products can be achieved.
For example, a curing agent for epoxy resin using isophoronediamine as a raw material has features such that it provides a coating film excellent in both gloss and levelling and a cured product excellent in both water resistance and chemical resistance compared with a curing agent for epoxy resin containing an aliphatic polyamino compound or a curing agent for epoxy resin using an aliphatic polyamino compound as a raw material. (See “New Development Of A Curing Agent For Epoxy Resin” edited by Hiroshi Kakiuchi, published by CMC Co. Ltd., P 41-49, May 31, 1994)
In general, a curing agent for epoxy resin is preferable to have a low viscosity from the viewpoint of workability. However, it is known that modified polyamines obtained by various modifications using polyamines as a raw material generally have a high viscosity and poor in workability.
Therefore, in order to achieve the purposes such as a reduction of harmful vapor, an improvement of the property of exothermic reaction at the time of curing and an improvement of an adhesion property, water resistance and chemical resistance of cured products and to obtain a curing agent for epoxy resin having a low viscosity, such method is generally employed that a polyamine is modified by reaction with the modification ratio increased and the reaction product thus obtained is diluted by a solvent and/or diluent to produce a curing agent for epoxy resin. However, a curing agent used for epoxy resin is recently expected to be a non-solvent agent because there is a strong tendency not to use a solvent from the viewpoint of the prevention of global environmental pollution. Thus, since it is desired to prevent the use of a solvent in terms of the environmental problem and the fact that the addition of a diluent is likely to cause the deterioration of the property of an epoxy resin cured product, it is necessary to restrict the addition amount of a solvent and/or diluent.
On the other hand, though it is possible to produce a modified polyamine having a low viscosity by the reaction with the modification ratio decreased, the reaction product thus obtained contains residual unreacted polyamine of the raw material in large quantity and it is difficult to yield good results in a reduction of harmful vapor, an improvement of the property of exothermic reaction at the time of curing and an improvement of an adhesion property, water resistance and chemical resistance of cured products.
Japanese Patent Kokai (Laid-open) No. 2002-161076 refers an amino compound obtained by modifying metaxylylenediamine or the like as a curing agent for epoxy resin and it discloses that this amino compound has a relatively low viscosity.